1. Field of the Invention
The present invention relates to a purified chondroitinase ABC and a crystallized chondroitinase ABC having an extremely high purity and excellent stability, a process for the preparation of the chondroitinase ABC and the chondroitinase ABC crystal, and a pharmaceutical composition comprising chondroitinase as an effective component.
2. Description of the Background Art
Chondroitinase ABC [EC 4.2.2.4] is an enzyme degrading hyaluronic acid, chondroitin sulfate, chondroitin, dermatan sulfate, or the like into a mixture of an unsaturated disaccharide and oligosaccharide. The enzyme is known to be produced by bacteria such as Proteus vulgaris.
For the preparation of chondroitinase ABC, a process which comprises subjecting a disrupted bacterial cell suspension progressively to a streptomycin treatment, an ammonium sulfate fractionation, a DEAE cellulose chromatography, and a phosphocellulose chromatography (J. Biol. Chem., 243, (7), 1523-1535 (1968)), and a process which comprises subjecting a disrupted bacterial cell suspension progressively to DEAE cellulose chromatography, hydroxyapatite chromatography, zinc-immobilized agarose chromatography, and gel permeation chromatography (Agric. Biol. Chem., 50, (4), 1057-1059 (1986); Japanese Patent Laid-open (kokai) No. 122588/1987), and the like are known.
On the other hand, the intervertebral disc dissolution method (Intradiscal therapy: chemonucleolysis) was developed for curing disc herniation which is identified as a cause of human lumbar pain. In this method, chymopapain which is a protease derived from papaya or a collagenase derived from bacteria is injected into the intervertebral disc antrum to remove the swelling capacity of the disc. Chymopapain is thus commercially sold in Europe and the United States as a drug under the trademark of Chymodiactin (Smith Laboratories) or Discase (Travenol).
However, the intradiscal therapy using said protease degrades not only the herniated disc, but also proteins in the surrounding tissues. This can be a cause of side effects such as neuroparalysis, allergy, and the like.
Mark R. Brown studied enzymes which can act on herniated disc with specificity and directed his attention to the degradation of proteoglycan which is a major herniated disc constituent. His study resulted in the intradiscal therapy using chondroitinase ABC or chondroitinase AC (U.S. Pat. No. 4,696,816).
In particular, the chondroitinase ABC produced by Proteus vulgaris is considered to be appropriate to medical and commercial applications because of its capability of selectively removing side chain of chondroitin sulfate or dermatan sulfate from proteoglycan, its inactivity toward keratan sulfate, heparin, and heparan sulfate, and its abundant productivity. Because of this, enzyme preparations having the chondroitinase ABC activity are prepared from culture products of Proteus vulgaris by aforementioned processes. These enzyme preparations, however, are not suitable for use as a drug for curing disc herniation or as a high-purity reagent, because they have protease activity or endotoxin activity and contain nucleic acid. They are unstable as enzyme proteins (J. Biol. Chem., 243, (7), 1523-1535 (1968); GB Patent 1067253, Agric. Biol. Chem., 50, (4), 1057-1059 (1986); Japanese Patent Laid-open (kokai) Nos. 122588/1987 and 57180/1990).
Especially, the presence of impurities and instability may cause serious problems when the chondroitinase ABC is used as a drug.